In climates where the temperature drops below the freezing point of water during the winter months, inground swimming pools are typically protected with a "winter cover". A winter cover is a sheet of material, e.g. polyvinylchloride ("vinyl") or other polymer, that is placed over the pool area. A winter cover is typically held in place with water bags, i.e. elongated tubular vinyl bags having closed ends and equipped with a capped filler neck, which are filled with water, capped and placed on top of the winter cover along the periphery of the pool to hold the cover in place.
Conventional water bags have a short life span, are prone to puncture damage and are somewhat awkward to use.